Direct link setup mechanisms for wireless LANs

ABSTRACT

A client station including a communication circuit to communicate, via an infrastructure mode, with an access point in a basic service set; identify, based on signals transmitted by the access point, a plurality of client stations in the basic service set capable of communicating via a direct link setup mode; and during a predetermined time period, communicate, via the direct link setup mode, with the plurality of client stations; and a control circuit to, during the predetermined time period, determine strength of signals received from the plurality of client stations via the direct link setup mode, determine highest supportable data rates for communicating with the plurality of client stations via the direct link setup mode, and select, based on (i) the strength of the signals and (ii) the highest supportable data rates, one or more of the plurality of client stations for communicating via the direct link setup mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/523,407,filed on Sep. 19, 2006. The entire disclosure of the applicationreferenced above is incorporated herein by reference.

BACKGROUND

The present invention relates generally to data communications. Moreparticularly, the present invention relates to direct link setupmechanisms for wireless local-area networks (WLAN).

Wireless local-area networks (WLAN) have become increasingly popular forcommunicating data between electronic devices. WLANs are frequentlyoperated in infrastructure mode, where a wireless access point relaysdata between the electronic devices, which are referred to as wirelessclients. Each communication between two wireless clients ininfrastructure mode requires two sequential transmissions: from thesending wireless client to the wireless access point, and from thewireless access point to the receiving wireless client. In many cases, adirect link between the two wireless clients would be preferable.

Direct link setup (DLS), which is described in IEEE standard 802.11e,provides this capability. FIG. 1 shows a conventional IEEE 802.11 WLAN100 comprising a wireless access point 102 passing traffic between twowireless clients 104A,B in infrastructure mode over connections 106A,Brespectively. DLS allows wireless clients 104A,B to establish a directconnection 108. However, DLS as specified by IEEE 802.11e has severallimitations.

IEEE 802.11e requires that wireless clients use the same channel for DLSas for the Basic Service Set (BSS) to which they belong. This is anunnecessary restriction if other channels are available for use.Furthermore, IEEE 802.11e DLS explicitly disables legacy power-save andAutomatic Power-Save Delivery (APSD), resulting in increased powerconsumption for wireless clients operating in DLS mode. IEEE 802.11e DLSalso does not define the precise conditions for initiating/tearing-downa DLS session or the operating parameters to be used during a DLSsession. In addition, IEEE 802.11e DLS does not specify a specificprotection mechanism to be used during DLS data transfer in order tomitigate interference from other traffic sources.

SUMMARY

In general, in one aspect, the invention features an apparatuscomprising: a communication circuit to establish an infrastructure modewireless connection with a wireless client through a wireless accesspoint, and to establish a direct link setup (DLS) mode wirelessconnection with the wireless client; and a control circuit to selecteither infrastructure mode or DLS mode for communication with thewireless client based on at least one characteristic of theinfrastructure mode and DLS mode wireless connections; wherein thecommunication circuit exchanges frames of data with the wireless clientusing the selected mode.

In some embodiments, the at least one characteristic of the wirelessconnections comprises at least one of the group consisting of: a qualityof service of the wireless connections; a power consumption of thewireless connections; a received signal strength of the wirelessconnections; a time required to send a frame over the wirelessconnections; a maximum data rate of the wireless connections; and apacket loss rate of the wireless connections. In some embodiments, thecommunication circuit receives a message from the wireless access pointthat identifies the media access control (MAC) address of the wirelessclient; and the control circuit identifies the wireless client based onthe message. In some embodiments, the message indicates whether thewireless client is capable of establishing a DLS connection. In someembodiments, before receiving the message from the wireless accesspoint, the communication circuit transmits a further message to thewireless access point that identifies one or more data stream typessupported by the apparatus; and the message received from the wirelessaccess point identifies the wireless client only when the wirelessclient supports the one or more data stream types supported by theapparatus. In some embodiments, the control circuit identifies thewireless client by collecting destination media access control (MAC)addresses in frames transmitted by the wireless access point. In someembodiments, the control circuit, after selecting DLS mode for thewireless client, selects infrastructure mode for the wireless client inresponse to an event. In some embodiments, the event is selected fromthe group consisting of: a received signal strength of a DLS connectionwith the wireless client falls below a predetermined threshold; and thecontrol circuit detects no frames addressed to the wireless clientduring a predetermined interval. In some embodiments, the controlcircuit determines proximity information for the wireless client, andselects the wireless client for DLS mode communications based on theproximity information. In some embodiments, the communication circuitestablishes the infrastructure mode wireless connection on a firstchannel; wherein the communication circuit establishes the DLS modewireless connection on a second channel; and wherein the control circuitselects the second channel when selecting DLS mode. In some embodiments,the control circuit causes the apparatus to enter a power-save mode;wherein the communication circuit receives beacon signals from thewireless access point while the apparatus is in the power-save mode; andwherein after every Nth beacon, wherein N>0, the control circuit causesthe apparatus to leave the power-save mode, then the communicationcircuit communicates with the wireless client when DLS mode has beenselected using the DLS mode connection, and then the control circuitcauses the apparatus to enter the power-save mode again. In someembodiments, the wireless client, when DLS mode has been selected,receives the beacon signals, leaves the power-save mode when the controlcircuit causes the apparatus to leave the power-save mode, and entersthe power-save mode when the control circuit causes the apparatus toenter the power-save mode. In some embodiments, the communicationcircuit transmits a message to the wireless access point informing thewireless access point that the apparatus is entering the power-savemode. In some embodiments, the communication circuit and the wirelessclient, when DLS mode has been selected, receive beacon signals from thewireless access point; wherein the control circuit establishes acommunications schedule with the wireless client according to the beaconsignals; wherein the control circuit causes the apparatus to leave apower-save mode, and then the communication circuit establishes a DLSconnection with the wireless client, according to the communicationsschedule; and wherein the wireless client leaves the power-save mode,and establishes a DLS connection with the apparatus, according to thecommunications schedule. In some embodiments, the communication circuittransmits a message to the wireless access point informing the wirelessaccess point that the apparatus is entering the power-save mode. Someembodiments comprise a media access controller (MAC) comprising theapparatus. Some embodiments comprise an integrated circuit comprisingthe MAC. Some embodiments comprise a wireless device comprising theintegrated circuit. In some embodiments, the wireless device iscompliant with all or part of IEEE standard 802.11, including draft andapproved amendments 802.11a, 802.11b, 802.11e, 802.11g, 802.11i,802.11k, 802.11n, 802.11v, and 802.11w.

In general, in one aspect, the invention features an apparatuscomprising: communication means for establishing an infrastructure modewireless connection with a wireless client through a wireless accesspoint, and for establishing a direct link setup (DLS) mode wirelessconnection with the wireless client; and control means for selectingeither infrastructure mode or DLS mode for communication with thewireless client based on at least one characteristic of theinfrastructure mode and DLS mode wireless connections; wherein thecommunication means exchanges frames of data with the wireless clientusing the selected mode.

In some embodiments, the at least one characteristic of the wirelessconnections comprises at least one of the group consisting of: a qualityof service of the wireless connections; a power consumption of thewireless connections; a received signal strength of the wirelessconnections; a time required to send a frame over the wirelessconnections; a maximum data rate of the wireless connections; and apacket loss rate of the wireless connections. In some embodiments, thecommunication means receives a message from the wireless access pointthat identifies the media access control (MAC) address of the wirelessclient; and wherein the control means identifies the wireless clientbased on the message. In some embodiments, the message indicates whetherthe wireless client is capable of establishing a DLS connection. In someembodiments, before receiving the message from the wireless accesspoint, the communication means transmits a further message to thewireless access point that identifies one or more data stream typessupported by the apparatus; and wherein the message received from thewireless access point identifies the wireless client only when thewireless client supports the one or more data stream types supported bythe apparatus. In some embodiments, the control means identifies thewireless client by collecting destination media access control (MAC)addresses in frames transmitted by the wireless access point. In someembodiments, the control means, after selecting DLS mode for thewireless client, selects infrastructure mode for the wireless client inresponse to an event. In some embodiments, the event is selected fromthe group consisting of: a received signal strength of a DLS connectionwith the wireless client falls below a predetermined threshold; and thecontrol means detects no frames addressed to the wireless client duringa predetermined interval. In some embodiments, the control meansdetermines proximity information for the wireless client, and selectsthe wireless client for DLS mode communications based on the proximityinformation. In some embodiments, the communication means establishesthe infrastructure mode wireless connection on a first channel; whereinthe communication means establishes the DLS mode wireless connection ona second channel; and wherein the control means selects the secondchannel when selecting DLS mode. In some embodiments, the control meanscauses the apparatus to enter a power-save mode; wherein thecommunication means receives beacon signals from the wireless accesspoint while the apparatus is in the power-save mode; and wherein afterevery Nth beacon, wherein N>0, the control means causes the apparatus toleave the power-save mode, then the communication means communicateswith the wireless client when DLS mode has been selected using the DLSmode connection, and then the control means causes the apparatus toenter the power-save mode again. In some embodiments, the wirelessclient, when DLS mode has been selected, receives the beacon signals,leaves the power-save mode when the control means causes the apparatusto leave the power-save mode, and enters the power-save mode when thecontrol means causes the apparatus to enter the power-save mode. In someembodiments, the communication means transmits a message to the wirelessaccess point informing the wireless access point that the apparatus isentering the power-save mode. In some embodiments, the communicationmeans and the wireless client, when DLS mode has been selected, receivebeacon signals from the wireless access point; wherein the control meansestablishes a communications schedule with the wireless client accordingto the beacon signals; wherein the control means causes the apparatus toleave a power-save mode, and then the communication means establishes aDLS connection with the wireless client, according to the communicationsschedule; and wherein the wireless client leaves the power-save mode,and establishes a DLS connection with the apparatus, according to thecommunications schedule. In some embodiments, the communication meanstransmits a message to the wireless access point informing the wirelessaccess point that the apparatus is entering the power-save mode. Someembodiments comprise a media access controller (MAC) comprising theapparatus. Some embodiments comprise an integrated circuit comprisingthe MAC. Some embodiments comprise a wireless device comprising theintegrated circuit. In some embodiments, the wireless device iscompliant with all or part of IEEE standard 802.11, including draft andapproved amendments 802.11a, 802.11b, 802.11e, 802.11g, 802.11i,802.11k, 802.11n, 802.11v, and 802.11w.

In general, in one aspect, the invention features a method comprising:establishing an infrastructure mode wireless connection with a wirelessclient through a wireless access point, and establishing a direct linksetup (DLS) mode wireless connection with the wireless client; andselecting either infrastructure mode or DLS mode for communication withthe wireless client based at least one characteristic of theinfrastructure mode and DLS mode wireless connections; and thenexchanging frames of data with the wireless client using the selectedmode.

In some embodiments, the at least one characteristic of the wirelessconnections comprises at least one of the group consisting of: a qualityof service of the wireless connections; a power consumption of thewireless connections; a received signal strength of the wirelessconnections; a time required to send a frame over the wirelessconnections; a maximum data rate of the wireless connections; and apacket loss rate of the wireless connections. Some embodiments compriseidentifying the wireless client by receiving a message from the wirelessaccess point that identifies the MAC address of the wireless client. Insome embodiments, the message indicates whether the wireless client iscapable of establishing a DLS connection. Some embodiments comprisebefore receiving the message from the wireless access point,transmitting a further message to the wireless access point thatidentifies one or more data stream types; wherein the message receivedfrom the wireless access point identifies the wireless client only whenthe wireless client supports the one or more data stream types. Someembodiments comprise identifying the wireless client by collectingdestination MAC addresses in frames transmitted by the wireless accesspoint. Some embodiments comprise after selecting DLS mode for thewireless client, selecting infrastructure mode for the wireless clientin response to an event. In some embodiments, the event is selected fromthe group consisting of: a received signal strength of a DLS connectionwith the wireless client falls below a predetermined threshold; and noframes addressed to the wireless client are detected during apredetermined interval. Some embodiments comprise determining proximityinformation for the wireless client; and selecting the wireless clientfor DLS mode communications based on the proximity information. Someembodiments comprise establishing the infrastructure mode wirelessconnection on a first channel; establishing the DLS wireless connectionon a second channel; and selecting the second channel when selecting DLSmode. Some embodiments comprise entering a power-save mode; receivingbeacon signals from the wireless access point while in the power-savemode; and after every Nth beacon, wherein N>0, leaving the power-savemode, then communicating with the wireless client when DLS mode has beenselected using DLS connections, and then entering the power-save modeagain. In some embodiments, the wireless client, when DLS mode has beenselected, receives the beacon signals, leaves the power-save mode whenthe method leaves the power-save mode, and enters power-save mode whenthe method enters the power-save mode. Some embodiments comprisereceiving beacon signals from the wireless access point, wherein thewireless client, when DLS mode has been selected, receives the beaconsignals from the wireless access point; establishing a communicationsschedule with the wireless client according to the beacon signals; andleaving a power-save mode, and establishing a DLS connection with thewireless client, according to the communications schedule; wherein thewireless client leaves the power-save mode, and establishes the DLSconnection, according to the communications schedule.

In general, in one aspect, the invention features a computer programexecutable on a processor, comprising: instructions for establishing aninfrastructure mode wireless connection with a wireless client through awireless access point, and for establishing a direct link setup (DLS)mode wireless connection with the wireless client; and instructions forselecting either infrastructure mode or DLS mode for communication withthe wireless client based at least one characteristic of theinfrastructure mode and DLS mode wireless connections; and theninstructions for exchanging frames of data with the wireless clientusing the selected mode.

In some embodiments, the at least one characteristic of the wirelessconnections comprises at least one of the group consisting of: a qualityof service of the wireless connections; a power consumption of thewireless connections; a received signal strength of the wirelessconnections; a time required to send a frame over the wirelessconnections; a maximum data rate of the wireless connections; and apacket loss rate of the wireless connections. Some embodiments compriseinstructions for identifying the wireless client according to a messagereceived from the wireless access point that identifies the MAC addressof the wireless client. In some embodiments, the message indicateswhether the wireless client is capable of establishing a DLS connection.Some embodiments comprise instructions for transmitting a furthermessage to the wireless access point that identifies one or more datastream types before receiving the message from the wireless accesspoint; wherein the message received from the wireless access pointidentifies the wireless client only when the wireless client supportsthe one or more data stream types. Some embodiments compriseinstructions for identifying the wireless client by collectingdestination MAC addresses in frames transmitted by the wireless accesspoint. Some embodiments comprise instructions for selectinginfrastructure mode for the wireless client in response to an eventafter selecting DLS mode for the wireless client. In some embodiments,the event is selected from the group consisting of: a received signalstrength of a DLS connection with the wireless client falls below apredetermined threshold; and no frames addressed to the wireless clientare detected during a predetermined interval. Some embodiments compriseinstructions for determining proximity information for the wirelessclient; and instructions for selecting the wireless client for DLS modecommunications based on the proximity information. Some embodimentscomprise instructions for establishing the infrastructure mode wirelessconnection on a first channel; instructions for establishing the DLSwireless connection on a second channel; and instructions for selectingthe second channel when selecting DLS mode. Some embodiments compriseinstructions for entering a power-save mode, wherein beacon signals arereceived from the wireless access point while in the power-save mode;and instructions for, after every Nth beacon, wherein N>0, leaving thepower-save mode, then communicating with the wireless client when DLSmode has been selected using DLS connections, and then entering thepower-save mode again. In some embodiments, the wireless client, whenDLS mode has been selected, receives the beacon signals, leaves thepower-save mode when the computer program leaves the power-save mode,and enters power-save mode when the computer program enters thepower-save mode. Some embodiments comprise, wherein beacon signals arereceived from the wireless access point, and wherein the wirelessclient, when DLS mode has been selected, receives the beacon signalsfrom the wireless access point; instructions for establishing acommunications schedule with the wireless client according to the beaconsignals; and instructions for leaving a power-save mode, andestablishing a DLS connection with the wireless client, according to thecommunications schedule; wherein the wireless client leaves thepower-save mode, and establishes the DLS connection, according to thecommunications schedule.

In general, in one aspect, the invention features a wireless accesspoint comprising: a communications circuit to communicate with aplurality of wireless clients; and a memory to store addresses of thewireless clients; wherein the communications circuit comprises atransmitter to transmit a message to at least one of the wirelessclients, wherein the message comprises the addresses of the wirelessclients, and identifies the wireless clients that are capable of directlink setup (DLS) mode communications.

In some embodiments, the addresses of the wireless clients are mediaaccess control (MAC) addresses. In some embodiments, the communicationscircuit comprises a receiver to receive a further message from the atleast one of the wireless clients, wherein the further message comprisesa request for the addresses of the wireless clients; and wherein thetransmitter transmits the message comprising the addresses of thewireless clients in response to the further message. In someembodiments, the communications circuit comprises a receiver to receiveone or more further messages from one or more of the wireless clients,wherein each of the further messages indicates one or more data streamtypes supported by the respective one of the one or more wirelessclients; and wherein the message comprising the addresses of thewireless clients includes only the addresses of wireless clientssupporting the data stream types supported by the wireless client towhich the message is transmitted.

In general, in one aspect, the invention features a wireless accesspoint comprising: communications means for communicating with aplurality of wireless clients; and memory means for storing addresses ofthe wireless clients; wherein the communications means comprisestransmitter means for transmitting a message to at least one of thewireless clients, wherein the message comprises the addresses of thewireless clients, and identifies the wireless clients that are capableof direct link setup (DLS) mode communications.

In some embodiments, the addresses of the wireless clients are mediaaccess control (MAC) addresses. In some embodiments, the communicationsmeans comprises receiver means for receiving a further message from theat least one of the wireless clients, wherein the further messagecomprises a request for the addresses of the wireless clients; andwherein the transmitter means transmits the message comprising theaddresses of the wireless clients in response to the further message. Insome embodiments, the communications means comprises receiver means forreceiving one or more further messages from one or more of the wirelessclients, wherein each of the further messages indicates one or more datastream types supported by the respective one of the one or more wirelessclients; and wherein the message comprising the addresses of thewireless clients includes only the addresses of wireless clientssupporting the data stream types supported by the wireless client towhich the message is transmitted.

In general, in one aspect, the invention features a method for awireless access point, the method comprising: communicating with aplurality of wireless clients; storing addresses of the wirelessclients; and transmitting a message to at least one of the wirelessclients, wherein the message comprises the addresses of the wirelessclients, and identifies the wireless clients that are capable of directlink setup (DLS) mode communications. In some embodiments, the addressesof the wireless clients are media access control (MAC) addresses. Someembodiments comprise receiving a further message from the at least oneof the wireless clients, wherein the further message comprises a requestfor the addresses of the wireless clients; and transmitting the messagecomprising the addresses of the wireless clients in response to thefurther message. Some embodiments comprise receiving one or more furthermessages from one or more of the wireless clients, wherein each of thefurther messages indicates one or more data stream types supported bythe respective one of the one or more wireless clients; and wherein themessage comprising the addresses of the wireless clients includes onlythe addresses of wireless clients supporting the data stream typessupported by the wireless client to which the message is transmitted.

In general, in one aspect, the invention features a computer programexecutable on a processor for a wireless access point, the computerprogram comprising: instructions for communicating with a plurality ofwireless clients; instructions for storing addresses of the wirelessclients; and instructions for transmitting a message to at least one ofthe wireless clients, wherein the message comprises the addresses of thewireless clients, and identifies the wireless clients that are capableof direct link setup (DLS) mode communications.

In some embodiments, the addresses of the wireless clients are mediaaccess control (MAC) addresses. Some embodiments comprise wherein thewireless access point receives a further message from the at least oneof the wireless clients, wherein the further message comprises a requestfor the addresses of the wireless clients; instructions for transmittingthe message comprising the addresses of the wireless clients in responseto the further message. In some embodiments, the wireless access pointreceives one or more further messages from one or more of the wirelessclients, wherein each of the further messages indicates one or more datastream types supported by the respective one of the one or more wirelessclients; and wherein the message comprising the addresses of thewireless clients includes only the addresses of wireless clientssupporting the data stream types supported by the wireless client towhich the message is transmitted.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a conventional IEEE 802.11 WLAN comprising a wirelessaccess point passing traffic between two wireless clients ininfrastructure mode.

FIG. 2 shows a IEEE 802.11 WLAN according to a preferred embodiment ofthe present invention.

FIG. 3 shows detail of the wireless client of FIG. 2 according to apreferred embodiment of the present invention.

FIG. 4 shows a process for the wireless client of FIG. 2 according to apreferred embodiment of the present invention.

FIG. 5 shows a process for the MAC of the wireless client FIG. 2according to a preferred embodiment of the present invention.

FIG. 6 shows a process for the MAC of the wireless client of FIG. 2 toemploy a power-save mechanism featuring a common DLS communicationwindow according to a preferred embodiment of the present invention.

FIG. 7 shows a process for the MAC of the wireless client of FIG. 2 toemploy a power-save mechanism featuring DLS communication schedulesestablished by DLS peers according to a preferred embodiment of thepresent invention.

FIG. 8 shows an example home entertainment system featuring wirelessclients capable of DLS communications according to a preferredembodiment of the present invention.

FIGS. 9A-9E show various exemplary implementations of the presentinvention.

The leading digit(s) of each reference numeral used in thisspecification indicates the number of the drawing in which the referencenumeral first appears.

DETAILED DESCRIPTION

Embodiments of the present invention provide various DLSimplementations. Some embodiments provide mechanisms for wirelessclients to use DLS connections on channels other than the channelutilized by the BSS to which the wireless clients belong. Someembodiments provide power-save mechanisms for wireless clients employingDLS connections. Some embodiments provide mechanisms for automatic setup and tear down of DLS connections at the link layer (OSI layer 2).Some embodiments provide mechanisms for protecting DLS connections frominterference generated by other traffic sources.

FIG. 2 shows an IEEE 802.11 WLAN 200 according to a preferred embodimentof the present invention. Although in the described embodiments, theelements of WLAN 200 are presented in one arrangement, other embodimentsmay feature other arrangements, as will be apparent to one skilled inthe relevant arts based on the disclosure and teachings provided herein.WLAN 200 comprises a wireless access point 202, a plurality of wirelessclients 204A-N, and a wireless client 210. Wireless client 210 cancommunicate with wireless clients 204 in infrastructure mode throughwireless access point 202 over connections 206, or directly via DLSconnections 208. Wireless client 210 is implemented according to one ormore embodiments of the present invention, while wireless clients 204can be implemented according to embodiments of the present invention, oras conventional wireless clients. Wireless access point 202 comprises awireless communication circuit 212 and a memory 214. Wirelesscommunication circuit 212 comprises a wireless transmitter 216 and awireless receiver 218.

FIG. 3 shows detail of wireless client 210 of FIG. 2 according to apreferred embodiment of the present invention. Although in the describedembodiments, the elements of wireless client 210 are presented in onearrangement, other embodiments may feature other arrangements, as willbe apparent to one skilled in the relevant arts based on the disclosureand teachings provided herein. For example, the elements of wirelessclient 210 can be implemented in hardware, software, or combinationsthereof. Wireless client 210 comprises a host 302, a media accesscontroller (MAC) 304, and a physical-layer device (PHY) 306. MAC 304comprises a communication circuit 308 and a control circuit 310. PHY 306comprises a baseband processor 312, a radio-frequency (RF) transceiver314, and an RF antenna 316. Wireless client 210 is preferably compliantwith all or part of IEEE standard 802.11, including draft and approvedamendments such as 802.11a, 802.11b, 802.11e, 802.11g, 802.11i, 802.11k,802.11n, 802.11v, and 802.11w.

FIG. 4 shows a process 400 for wireless client 210 of FIG. 2 accordingto a preferred embodiment of the present invention. Although in thedescribed embodiments, the elements of process 400 are presented in onearrangement, other embodiments may feature other arrangements, as willbe apparent to one skilled in the relevant arts based on the disclosureand teachings provided herein. Wireless client 210 first determineswhich wireless clients 204 are candidates for DLS connections (step402).

In some embodiments, wireless access point 202 creates a list ofaddresses, such as MAC or IP addresses, associated with the wirelessclients 204, 210, stores the list in memory 214, and transmits a messageto wireless client 210 that includes the list of addresses. In someembodiments, wireless client 210 sends a message to wireless accesspoint 202 to request the list, and wireless access point 202 transmits amessage comprising the list in response. IEEE 802.11 action managementframes can be used for this purpose.

In some embodiments, the list also indicates which wireless clients 204,210 are capable of DLS connections. Wireless access point 202 canassemble the list based on messages received from wireless clients 204,210 that identify the DLS capabilities of wireless clients 204, 210.

In some embodiments, each wireless client 204, 210 can indicate the datastream types it will accept. For example, a wireless video playbackdevice can indicate that it will accept only video data streams. Inthese embodiments, wireless access point 202 can tailor the messages sothat each wireless client 204, 210 is included only in lists sent towireless clients 204, 210 that support the data stream types specifiedby that wireless client 204, 210.

In some embodiments, wireless clients 204, 210 broadcast messages thatindicate their DLS capabilities, for example at some random backoffinterval following beacons transmitted by wireless access point 202.Preferably each message includes the BSSID so that it is only used bywireless clients in the same BSS.

In some embodiments, control circuit 310 of wireless client 210 createsthe list of DLS candidates by collecting the addresses, such as MAC orIP addresses, in frames transmitted by wireless access point 202.

Referring again to process 400 of FIG. 4, wireless client 210 nextdiscovers DLS peers among the DLS candidates. That is, wireless client210 determines which of the wireless clients 204 determined to becandidates for DLS connections in step 402 are reachable by DLSconnections (step 404). Preferably communication circuit 308 establishesa DLS mode wireless connection with each DLS candidate, and if the DLSconnection is successful, adds the DLS candidate to a list of DLS peers.Preferably each of these “test” DLS connections is used to exchangequality of service (QoS) information between the DLS peers. In someembodiments, each test DLS connection has a DLS Timeout value on theorder of one second. In other embodiments, each test DLS connection istorn down explicitly.

Referring again to process 400 of FIG. 4, wireless client 210 agesand/or filters the list of DLS peers to remove wireless clients 204 thatare no longer suitable as DLS peers (step 406). In some embodiments,control circuit 310 of wireless client 210 removes a wireless client 204from its DLS peer list when a received signal strength of a DLSconnection with the wireless client 204 falls below a predeterminedthreshold. For example, the received signal strength can be determinedbased upon a received signal strength indication (RSSI). In someembodiments, control circuit 310 of wireless client 210 removes awireless client 204 from the DLS peer list when control circuit 310detects no frames addressed to that wireless client 204 during apredetermined interval.

Referring again to process 400 of FIG. 4, wireless client 210 discoversthe DLS topology of its DLS peers (step 408). That is, control circuit310 of wireless client 210 determines proximity information representingthe proximity of each wireless client 204 in the DLS peer list. Theproximities can be used, for example, to select among similar resources.For example, when a video stream is available from more than one peer,control circuit 310 can select the most proximate peer to obtain thebest DLS connection for transfer of the video stream.

In some embodiments, the proximity for each peer is determined basedupon the RSSI and supportable transmission rates for a DLS connectionwith that peer. During the DLS connection, wireless client 210 monitorsthe RSSI of the received frames as well as the data rates used forsuccessful transmission. To minimize overhead, wireless client 210transmits Data Null frames at various rates and notes the highestsupportable transmit rate (MaxDLSrate) to each DLS peer. As part of theDLS Request/Response handshake, wireless client 210 also obtains the QoScapabilities of each DLS peer, which are used in establishingMaxDLSrate. The MaxDLSRate, along with the received RSSI, provides anestimate of the proximity of the DLS peer.

Preferably process 400 repeats occasionally (for example by returning tostep 402) to determine whether new DLS candidates have entered the BSSof wireless access point 202.

In some cases, even though DLS mode communications are possible with aDLS peer, it is preferable to communicate with the peer usinginfrastructure mode communications, for example because aninfrastructure mode connection provides higher data rates than a DLSmode connection. In some embodiments, MAC 304 of wireless client 210automatically selects either infrastructure mode communications or DLSmode communications independently for each of its DLS peers.

FIG. 5 shows a process 500 for MAC 304 of wireless client 210 of FIG. 2according to a preferred embodiment of the present invention. Althoughin the described embodiments, the elements of process 500 are presentedin one arrangement, other embodiments may feature other arrangements, aswill be apparent to one skilled in the relevant arts based on thedisclosure and teachings provided herein.

Communication circuit 308 of MAC 304 establishes at least oneinfrastructure mode wireless connection with each of the wirelessclients 204 through wireless access point 202 (step 502). Preferably thewireless clients 204 are selected from the peer list created by process400 of FIG. 4.

Control circuit 310 determines at least one characteristic of each ofthe infrastructure mode wireless connections (step 504). For example,the characteristics can include one or more of: a quality of service ofthe wireless connection, a power consumption of the wireless connection,a received signal strength of the wireless connection, a time requiredto send a frame over the wireless connection, a maximum data rate of thewireless connection, and a packet loss rate of the wireless connection.

Communication circuit 308 of MAC 304 establishes at least one DLS modewireless connection with each of the wireless clients 204 (step 506).Control circuit 310 determines at least one characteristic, such asthose described above, of each of the DLS mode wireless connections(step 508). In some embodiments, communication circuit 308 establishesthe DLS connections for each wireless client 204 in multiple channels,and selects the best channel as the preferred DLS channel for thatwireless client 204. This information can be maintained in the DLS peerlist.

Control circuit 310 of MAC 304 selects either infrastructure mode or DLSmode for communication with each of the wireless clients 204 based on atleast one of the characteristics of the respective infrastructure modeand DLS mode wireless connections (step 510). In some embodiments,wireless client 210 determines the maximum data rate at which packetloss is minimized, for both DLS mode and infrastructure mode, for awireless client 204, and then selects the mode with the lower packetloss rate for that wireless client 204. In the event both modes havesimilar packet loss rates, wireless client 210 selects the mode with thelower power consumption. Power consumption can be determined in manywell-known ways. One way is to determine the average time spent stayingawake, time spent in transmit mode and time spent in receive mode.

In some embodiments, wireless client 210 determines the amount of timeit takes to unicast a block of data at the maximum data rate, for bothDLS mode and infrastructure mode, for a wireless client 204, and thenselects the mode with the lower transit time for that wireless client204. Packet loss and/or power consumption can be used as additionalmetrics in this example.

Communication circuit 308 of MAC 304 then exchanges frames of data witheach wireless client 204 using the mode selected for that wirelessclient 204 (step 512). Preferably all or part of process 500 repeatsoccasionally (for example by returning to step 502), for example toaccommodate changes to the list of DLS peers, or to accommodate changesin topology that could affect selection of communication mode.

In some embodiments, wireless clients 204, 210 employ a power-savemechanism featuring a common DLS communication window establishedaccording to the beacon signal transmitted by wireless access point 202.According to these embodiments, after every beacon, (or every N beacons,where N can be negotiated between DLS peers), a DLS communication windowis defined. All DLS peers must stay awake during this predeterminedwindow. A DLS peer can announce its intent to communicate with anotherDLS peer during the window. The DLS peers which agree to communicateduring the window stay awake to complete that communication. At the endof the communication (which can be indicated by explicit signaling), theDLS peers can go to sleep immediately. The end of communicationindication can be sent as a separate message or can be piggybacked (bysetting a reserved bit in the MAC header) on the last message sent by apeer.

FIG. 6 shows a process 600 for MAC 304 of wireless client 210 of FIG. 2that employs a power-save mechanism featuring a common DLS communicationwindow according to a preferred embodiment of the present invention.Although in the described embodiments, the elements of process 600 arepresented in one arrangement, other embodiments may feature otherarrangements, as will be apparent to one skilled in the relevant artsbased on the disclosure and teachings provided herein.

Control circuit 310 causes wireless client 210 to enter a power-savemode (step 602). Communication circuit 308 remains awake to receivebeacon signals from wireless access point 202 while wireless client 210is in the power-save mode (step 604).

After every Nth beacon (step 606), where N>0, control circuit 310 causeswireless client 210 to leave the power-save mode (step 608).Communication circuit 308 then communicates with the wireless clients204 for which DLS mode has been selected using DLS connections (step610). Then control circuit 310 causes wireless client 210 to enter thepower-save mode again (step 612). Preferably process 600 repeats (forexample, by returning to step 604).

In some embodiments, wireless clients 204, 210 employ a power-savemechanism featuring DLS communication schedules established by DLS peersaccording to the beacon signal transmitted by wireless access point 202.According to these embodiments, DLS peers negotiate communicationschedules based on a common timer synchronization function (TSF), whichthey receive from the beacon signal transmitted by wireless access point202. The schedule can specify a start time and a communication interval,thus defining a series of communication windows separated by fixedintervals. Both DLS peers leave power-save mode at each scheduled starttime, communicate during the communication window, and then resumepower-save mode.

FIG. 7 shows a process 700 for MAC 304 of wireless client 210 of FIG. 2that employs a power-save mechanism featuring DLS communicationschedules established by DLS peers according to a preferred embodimentof the present invention. Although in the described embodiments, theelements of process 700 are presented in one arrangement, otherembodiments may feature other arrangements, as will be apparent to oneskilled in the relevant arts based on the disclosure and teachingsprovided herein.

Communication circuit 308 receives beacon signals from wireless accesspoint 202 (step 702). Control circuit 310 establishes a communicationsschedule with one of wireless clients 204 according to the beaconsignals transmitted by wireless access point 202 (step 704). Controlcircuit 310 causes wireless client 210 to leave power-save modeaccording to the communications schedule (step 706). Communicationcircuit 308 then establishes a DLS connection with the wireless client204 (step 708) and exchanges data with the wireless client 204 (step710). Control circuit 310 then causes wireless client 210 to enterpower-save mode according to the communications schedule (step 712).Preferably process 700 repeats (for example, by returning to step 706).

In some embodiments, while remaining a member of the BSS it isassociated with (the main BSS), wireless client 210 can operate asub-BSS or establish a DLS connection in a channel different from thatof the main BSS, thus allowing reduction of interference and improvedperformance. To wireless access point 202, it appears that the wirelessclients 210 in a sub-BSS are operating in a power-save mode. Therefore,wireless access point 202 does not forward frames to the wirelessclients 210 in a sub-BSS. All stations in the sub-BSSs remainsynchronized to the main BSS by periodically listening for beacons fromwireless access point 202 in the main BSS. Wireless client 210 canemploy process 400 of FIG. 4 and/or process 500 of FIG. 5 in the sub-BSSto automatically establish DLS connections with other wireless clients204 in the sub-BSS. Wireless clients 204, 210 in the sub-BSS canschedule test DLS connections according to the beacon transmitted bywireless access point 202. One advantage of using a DLS connection in asub-BSS in a channel different than that of the main BSS is that the DLSconnection is protected from interference from the main BSS.

In some embodiments, wireless client 210 informs wireless access point202 when entering power-save mode. For example, communication circuit212 transmits a message to wireless access point 202 informing wirelessaccess point 202 that wireless client 210 is entering power-save mode.In some embodiments, a pair of wireless clients 210, before initiating aDLS connection, determine whether wireless access point 202 honorspower-save mode for clients in DLS mode. For example, after informingwireless access point 202 that wireless clients are entering power-savemode, wireless clients 210 can exchange traffic through wireless accesspoint 202. If wireless access point 202 buffers the traffic, and setsthe appropriate Traffic Indication Map (TIM) bits in the beacon, thenwireless access point honors power-save mode for clients in DLS mode.

FIG. 8 shows an example home entertainment system 800 featuring wirelessclients capable of DLS communications according to a preferredembodiment of the present invention. Home entertainment system 800includes a personal video recorder (PVR) 802 connected to a televisionset (TV) 804, an mp3 player 806, a movie camera 808, and a wirelessaccess point 810. Each of PVR 802, mp3 player 806, and camera 808 areimplemented as wireless devices according to preferred embodiments ofthe present invention, and are associated with wireless access point810. For example, each of PVR 802, mp3 player 806, and camera 808include a wireless client 812A,B,C such as wireless client 210 of FIG.2.

Each of the wireless devices (PVR 802, mp3 player 806, and camera 808)can cache media content that may not be available on others of thedevices. For example, PVR 802 can store movies, such as recordings oftelevision programs, and music, such as mp3 files. The mp3 player 806can store music files. Camera 808 can store movies. These wirelessdevices can discover each other, identify content desired by users, anddetermine the most suitable peer device for obtaining the content. Homeentertainment system 800 allows the content to be transferred among thewireless devices using DLS connections, without going through wirelessaccess point 810, according to the techniques described above, therebyproviding more efficient utilization of channel resources and betterperformance than a purely infrastructure wireless WLAN.

FIGS. 9A-9E show various exemplary implementations of the presentinvention. Referring now to FIG. 9A, the present invention can beimplemented in a high definition television (HDTV) 912. The presentinvention may implement either or both signal processing and/or controlcircuits, which are generally identified in FIG. 9A at 913, a WLANinterface and/or mass data storage of the HDTV 912. The HDTV 912receives HDTV input signals in either a wired or wireless format andgenerates HDTV output signals for a display 914. In someimplementations, signal processing circuit and/or control circuit 913and/or other circuits (not shown) of the HDTV 912 may process data,perform coding and/or encryption, perform calculations, format dataand/or perform any other type of HDTV processing that may be required.

The HDTV 912 may communicate with mass data storage 915 that stores datain a nonvolatile manner such as optical and/or magnetic storage devices.The HDD may be a mini HDD that includes one or more platters having adiameter that is smaller than approximately 1.8″. The HDTV 912 may beconnected to memory 916 such as RAM, ROM, low latency nonvolatile memorysuch as flash memory and/or other suitable electronic data storage. TheHDTV 912 also may support connections with a WLAN via a WLAN networkinterface 917.

Referring now to FIG. 9B, the present invention implements a controlsystem of a vehicle 918, a WLAN interface and/or mass data storage ofthe vehicle control system. In some implementations, the presentinvention implements a powertrain control system 919 that receivesinputs from one or more sensors such as temperature sensors, pressuresensors, rotational sensors, airflow sensors and/or any other suitablesensors and/or that generates one or more output control signals such asengine operating parameters, transmission operating parameters, and/orother control signals.

The present invention may also be implemented in other control systems922 of the vehicle 918. The control system 922 may likewise receivesignals from input sensors 923 and/or output control signals to one ormore output devices 924. In some implementations, the control system 922may be part of an anti-lock braking system (ABS), a navigation system, atelematics system, a vehicle telematics system, a lane departure system,an adaptive cruise control system, a vehicle entertainment system suchas a stereo, DVD, compact disc and the like. Still other implementationsare contemplated.

The powertrain control system 919 may communicate with mass data storage925 that stores data in a nonvolatile manner. The mass data storage 925may include optical and/or magnetic storage devices for example harddisk drives HDD and/or DVDs. The HDD may be a mini HDD that includes oneor more platters having a diameter that is smaller than approximately1.8″. The powertrain control system 919 may be connected to memory 926such as RAM, ROM, low latency nonvolatile memory such as flash memoryand/or other suitable electronic data storage. The powertrain controlsystem 919 also may support connections with a WLAN via a WLAN networkinterface 927. The control system 922 may also include mass datastorage, memory and/or a WLAN interface (all not shown).

Referring now to FIG. 9C, the present invention can be implemented in acellular phone 928 that may include a cellular antenna 929. The presentinvention may implement either or both signal processing and/or controlcircuits, which are generally identified in FIG. 9C at 930, a WLANinterface and/or mass data storage of the cellular phone 928. In someimplementations, the cellular phone 928 includes a microphone 931, anaudio output 932 such as a speaker and/or audio output jack, a display933 and/or an input device 934 such as a keypad, pointing device, voiceactuation and/or other input device. The signal processing and/orcontrol circuits 930 and/or other circuits (not shown) in the cellularphone 928 may process data, perform coding and/or encryption, performcalculations, format data and/or perform other cellular phone functions.

The cellular phone 928 may communicate with mass data storage 935 thatstores data in a nonvolatile manner such as optical and/or magneticstorage devices for example hard disk drives HDD and/or DVDs. The HDDmay be a mini HDD that includes one or more platters having a diameterthat is smaller than approximately 1.8″. The cellular phone 928 may beconnected to memory 936 such as RAM, ROM, low latency nonvolatile memorysuch as flash memory and/or other suitable electronic data storage. Thecellular phone 928 also may support connections with a WLAN via a WLANnetwork interface 937.

Referring now to FIG. 9D, the present invention can be implemented in aset top box 938. The present invention may implement either or bothsignal processing and/or control circuits, which are generallyidentified in FIG. 9D at 939, a WLAN interface and/or mass data storageof the set top box 938. The set top box 938 receives signals from asource such as a broadband source and outputs standard and/or highdefinition audio/video signals suitable for a display 940 such as atelevision and/or monitor and/or other video and/or audio outputdevices. The signal processing and/or control circuits 939 and/or othercircuits (not shown) of the set top box 938 may process data, performcoding and/or encryption, perform calculations, format data and/orperform any other set top box function.

The set top box 938 may communicate with mass data storage 943 thatstores data in a nonvolatile manner. The mass data storage 943 mayinclude optical and/or magnetic storage devices for example hard diskdrives HDD and/or DVDs. The HDD may be a mini HDD that includes one ormore platters having a diameter that is smaller than approximately 1.8″.The set top box 938 may be connected to memory 942 such as RAM, ROM, lowlatency nonvolatile memory such as flash memory and/or other suitableelectronic data storage. The set top box 938 also may supportconnections with a WLAN via a WLAN network interface 943.

Referring now to FIG. 9E, the present invention can be implemented in amedia player 944. The present invention may implement either or bothsignal processing and/or control circuits, which are generallyidentified in FIG. 9E at 945, a WLAN interface and/or mass data storageof the media player 944. In some implementations, the media player 944includes a display 946 and/or a user input 947 such as a keypad,touchpad and the like. In some implementations, the media player 944 mayemploy a graphical user interface (GUI) that typically employs menus,drop down menus, icons and/or a point-and-click interface via thedisplay 946 and/or user input 947. The media player 944 further includesan audio output 948 such as a speaker and/or audio output jack. Thesignal processing and/or control circuits 945 and/or other circuits (notshown) of the media player 944 may process data, perform coding and/orencryption, perform calculations, format data and/or perform any othermedia player function.

The media player 944 may communicate with mass data storage 949 thatstores data such as compressed audio and/or video content in anonvolatile manner. In some implementations, the compressed audio filesinclude files that are compliant with MP3 format or other suitablecompressed audio and/or video formats. The mass data storage may includeoptical and/or magnetic storage devices for example hard disk drives HDDand/or DVDs. The HDD may be a mini HDD that includes one or moreplatters having a diameter that is smaller than approximately 1.8″. Themedia player 944 may be connected to memory 950 such as RAM, ROM, lowlatency nonvolatile memory such as flash memory and/or other suitableelectronic data storage. The media player 944 also may supportconnections with a WLAN via a WLAN network interface 951. Still otherimplementations in addition to those described above are contemplated.

Embodiments of the invention can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. Apparatus of the invention can be implemented in acomputer program product tangibly embodied in a machine-readable storagedevice for execution by a programmable processor; and method steps ofthe invention can be performed by a programmable processor executing aprogram of instructions to perform functions of the invention byoperating on input data and generating output. The invention can beimplemented advantageously in one or more computer programs that areexecutable on a programmable system including at least one programmableprocessor coupled to receive data and instructions from, and to transmitdata and instructions to, a data storage system, at least one inputdevice, and at least one output device. Each computer program can beimplemented in a high-level procedural or object-oriented programminglanguage, or in assembly or machine language if desired; and in anycase, the language can be a compiled or interpreted language. Suitableprocessors include, by way of example, both general and special purposemicroprocessors. Generally, a processor will receive instructions anddata from a read-only memory and/or a random access memory. Generally, acomputer will include one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of nonvolatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM disks. Any of the foregoing canbe supplemented by, or incorporated in, ASICs (application-specificintegrated circuits).

A number of implementations of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other implementations are within the scope of the followingclaims.

What is claimed is:
 1. A client station comprising: a communicationcircuit configured to communicate, via an infrastructure mode, with anaccess point in a basic service set, identify, based on signalstransmitted by the access point, a plurality of client stations in thebasic service set capable of communicating via a direct link setup mode,and communicate, via the direct link setup mode, with the plurality ofclient stations; and a control circuit configured to determine strengthof signals received from the plurality of client stations via the directlink setup mode; determine highest supportable data rates forcommunicating with the plurality of client stations via the direct linksetup mode; select, based on (i) the strength of the signals receivedfrom the plurality of client stations via the direct link setup mode and(ii) the highest supportable data rates, one or more of the plurality ofclient stations for communicating via the direct link setup mode; andnegotiate a communication schedule with the one or more of the pluralityof client stations based on a common timer synchronization functionreceived by the one or more of the plurality of client stations frombeacons transmitted by the access point, wherein the communicationschedule (i) specifies a start time and a communication interval tocommunicate with the one or more of the plurality of client stations viathe direct link setup mode, and (ii) includes a series of communicationwindows separated by fixed intervals.
 2. The client station of claim 1,wherein the control circuit is configured to select (i) a first channelto communicate with the access point via the infrastructure mode and(ii) a second channel to communicate with the one or more of theplurality of client stations via the direct link setup mode, wherein thesecond channel is different than the first channel.
 3. The clientstation of claim 1, wherein: the communication circuit is configured tocommunicate with a first client station of the one or more of theplurality of client stations at a data rate via (i) the infrastructuremode and (ii) the direct link setup mode; and the control circuit isconfigured to determine packet loss rates while the communicationcircuit is communicating with the first client station via (i) theinfrastructure mode and (ii) the direct link setup mode, and select (i)the infrastructure mode or (ii) the direct link setup mode having alower packet loss rate to communicate with the first client station. 4.The client station of claim 1, wherein: the communication circuit isconfigured to communicate with a first client station of the one or moreof the plurality of client stations at a data rate via (i) theinfrastructure mode and (ii) the direct link setup mode; and the controlcircuit is configured to determine packet loss rates while thecommunication circuit is communicating with the first client station via(i) the infrastructure mode and (ii) the direct link setup mode, andselect, based on the packet loss rates of (i) the infrastructure modeand (ii) the direct link setup mode, (i) the infrastructure mode or (ii)the direct link setup mode having a lower power consumption tocommunicate with the first client station.
 5. The client station ofclaim 1, wherein: the communication circuit is configured to unicast ablock of data at a data rate to a first client station of the one ormore of the plurality of client stations via (i) the infrastructure modeand (ii) the direct link setup mode; and the control circuit isconfigured to select, to communicate with the first client station, (i)the infrastructure mode or (ii) the direct link setup mode having alower transit time while unicasting the block of data at the data rateto the first client station.
 6. The client station of claim 1, whereinthe control circuit is configured to cause the client station to: entera power save mode in response to selecting the direct link setup mode tocommunicate with a first client station from the one or more of theplurality of client stations, leave the power save mode at the starttime of one of the communication windows, communicate with the firstclient station via the direct link setup mode during the one of thecommunication windows, and resume the power save mode at an end of thecommunication interval of the one of the communication windows.
 7. Amethod comprising: Communicating, via an infrastructure mode, with anaccess point in a basic service set; identifying, at a client station,based on signals transmitted by the access point, a plurality of clientstations in the basic service set capable of communicating via a directlink setup mode; communicating, via the direct link setup mode, with theplurality of client stations; determining strength of signals receivedat the client station from the plurality of client stations via thedirect link setup mode; determining highest supportable data rates forcommunicating with the plurality of client stations via the direct linksetup mode; selecting, based on (i) the strength of the signals receivedfrom the plurality of client stations via the direct link setup mode and(ii) the highest supportable data rates, one or more of the plurality ofclient stations for communicating via the direct link setup mode; andnegotiating a communication schedule with the one or more of theplurality of client stations based on a common timer synchronizationfunction received by the one or more of the plurality of client stationsfrom beacons transmitted by the access point, wherein the communicationschedule (i) specifies a start time and a communication interval tocommunicate with the one or more of the plurality of client stations viathe direct link setup mode, and (ii) includes a series of communicationwindows separated by fixed intervals.
 8. The method or claim 7, furthercomprising selecting (i) a first channel to communicate with the accesspoint via the infrastructure mode and (ii) a second channel tocommunicate with the one or more of the plurality of client stations viathe direct link setup mode, wherein the second channel is different thanthe first channel.
 9. The method of claim 7, further comprising:communicating with a first client station of the one or more of theplurality of client stations at a data rate via (i) the infrastructuremode and (ii) the direct link setup mode; determining packet loss rateswhile communicating with the first client station via (i) theinfrastructure mode and (ii) the direct link setup mode; and selecting(i) the infrastructure mode or (ii) the direct link setup mode having alower packet loss rate to communicate with the first client station. 10.The method of claim 7, further comprising: communicating with a firstclient station of the one or more of the plurality of client stations ata data rate via (i) the infrastructure mode and (ii) the direct linksetup mode; determining packet loss rates while communicating with thefirst client station via (i) the infrastructure mode and (ii) the directlink setup mode; and selecting, based on the packet loss rates of (i)the infrastructure mode and (ii) the direct link setup mode, (i) theinfrastructure mode or (ii) the direct link setup mode having a lowerpower consumption to communicate with the first client station.
 11. Themethod of claim 7, further comprising: unicasting a block of data at adata rate to a first client station from the one or more of theplurality of client stations via (i) the infrastructure mode and (ii)the direct link setup mode; and selecting, to communicate with the firstclient station, (i) the infrastructure mode or (ii) the direct linksetup mode having a lower transit time while unicasting the block ofdata at the data rate to the first client station.
 12. The method ofclaim 7, further comprising causing the client station to: enter a powersave mode in response to selecting the direct link setup mode tocommunicate with a first client station of the one or more of theplurality of client stations, leave the power save mode at the starttime of one of the communication windows, communicate with the firstclient station via the direct link setup mode during the one of thecommunication windows, and resume the power save mode at an end of thecommunication interval of the one of the communication windows.